In minimally invasive surgical procedures, one or more tissue layers must sometimes be punctured without direct visualization of an instrument tip in order to gain access to a body cavity, duct, or the like. The instruments for such procedures are generally long and slender with high axial stiffness. In use, a surgeon or other user applies sufficient axial force so that the instrument can penetrate into the tissue by cutting, tearing or separating tissue fibers.
At the point of puncture, or the instant when the tissue opens at the tip of the instrument, the force applied to the instrument by tissue tension goes to zero while the force applied by the user remains as a net force accelerating the instrument into the surgical site. Device designers have attempted to improve instruments to mitigate this forward driving force and subsequent acceleration by offering dynamic blade covers, blunt-tipped devices, and other features that indirectly address the problem of over-puncture by seeking to reduce the harmful effects when an over-puncture occurs.
There remains a need for puncture devices that reduce or eliminate the over-puncture event, rather than addressing consequences of an over-puncture after it occurs. There remains a further need for a puncture device that locks in a preloaded state for improved ease of use.